This invention relates generally to foot prostheses and, more particularly, to foot prostheses configured to duplicate the dynamic performance characteristics of the human foot and ankle.
Significant advancements in the field of foot prostheses have been made in recent years, due largely to the development of composite materials technology. Foot prostheses incorporating fiberglass/epoxy and carbon fiber/epoxy composite materials have been developed, which closely duplicate the dynamic performance characteristics of the human foot and ankle.
One such foot prosthesis is disclosed in U.S. Pat. No. 4,959,073 issued to Merlette. The Merlette prosthesis incorporates an elongated composite main member having a leg section and a forwardly extending foot section, and it further incorporates a heel member projecting rearwardly from the underside of the main member's foot section. A high-density polyurethane elastomer is disposed between the heel member and the main member's foot section, to permanently attach the two members together and to provide limited cushioning. The upper end of the main member's leg section supports an amputation socket for receiving the amputee's residual limb, and a crepe sole can be attached to the underside of the heel member. A foam foot shell or cosmesis can be placed over the composite members, to provide the prosthesis with an appearance of a normal human foot.
The Merlette foot prosthesis described briefly above has enjoyed substantial commercial success. Nevertheless, it is believed that the Merlette prosthesis can be improved upon by simplifying its manufacture, thus reducing both material and labor costs, and by minimizing the possibility of component failure.
Users of foot prostheses of this kind typically will desire to use the prosthesis while wearing a variety of shoes having heels of different heights. One drawback to prior foot prostheses is that they typically have been configured to have a fixed heel height. They typically have not been configured to provide for a convenient adjustment of their heel height, to allow the user to use the prosthesis with a variety of shoes.
Users of foot prostheses of this kind typically also will desire to use the prosthesis in a variety of physical activities. Some of these activities will be best engaged in using a prosthesis having relatively high stiffness, while others will be best engaged in using a prosthesis having relatively low stiffness, or high compliance. Despite this desire, foot prostheses generally have not been configured to provide for a convenient adjustment of their stiffnesses.
It should therefore be appreciated that there exists a need for a foot prosthesis that can be manufactured more economically and that is configured to facilitate a convenient adjustment of its heel height and its stiffness. The present invention fulfills this need and provides further related advantages.